<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .nav {
            width: 800px;
            height: 2000px;
            background-color: springgreen;
            margin: 0 auto;
        }
        .dj {
            /* 利用left 向右移动百分之五十，到达版心中间，之后在加上半个版心的距离，就刚好靠在版心右侧 */
            position: fixed;
            bottom: 50px;
            left: 50%;
            margin-left: 400px;
        }
    </style>
</head>
<body>
    <div class="nav">
        <div class="dj">
            <img src="images/pvp.png" alt="">
        </div>
    </div>
</body>
</html>